Police have seen a spike in thefts of catalytic converters from vehicles in recent years, especially in California, according to a new video report based on data from the National Insurance Crime Bureau (NICB).

Thieves stole nearly 4,000 catalytic converters in the four years between 2012 and 2015. In 2009, thieves stole 1,058 parts. Thefts peaked in 2014, when 4,370 catalytic converters were stolen, according to the bureau. 

The part helps convert poisonous carbon monoxide into harmless carbon dioxide. They contain small amounts of valuable metals such as platinum, palladium, or rhodium, and are typically easy to unbolt or cut off vehicles.

Criminals simply saw off the converter from the exhaust system and then sell the part to salvage yards. A typical converter can fetch approximately $200, but it will cost the vehicle owner victim an estimated $1,000 to replace, according to the bureau.

Some states are considering enacting laws that would require a seller to present identification to salvage dealers so that the stolen converters can be traced, according to the report. 

Related: Component Theft and Vandalism: A Growing Expense for Truck Fleet Managers